XScreenSaver(1)

NAME
xscreensaver-command - control a running xscreensaver process

SYNOPSIS
xscreensaver-command [-display host:display.screen] [-help] [-demo] [-prefs] [-activate] [-deactivate] [-cycle] [-next] [-prev] [-select n] [-exit] [-restart] [-lock] [-throttle] [-unthrottle] [-version] [-time] [-watch]

DESCRIPTION
The xscreensaver-command program controls a running xscreensaver process by sending it client-messages. xscreensaver(1) has a client-server model: the xscreensaver process is a daemon that runs in the background; it is controlled by other foreground programs such as xscreensaver-command and xscreensaver-demo(1). This program, xscreensaver-command, is a command-line-oriented tool; the xscreensaver-demo(1). program is a graphical tool.

OPTIONS
xscreensaver-command accepts the following command-line options:

-help
    Prints a brief summary of command-line options.

-demo
    This just launches the xscreensaver-demo(1) program, in which one can experiment with the various graphics hacks available, and edit parameters.

-demo number
    When the -demo option is followed by an integer, it instructs the xscreensaver daemon to run that hack, and wait for the user to click the mouse before deactivating (i.e., mouse motion does not deactivate.) This is the mechanism by which xscreensaver-demo(1) communicates with the xscreensaver(1) daemon. (The first hack in the list is numbered 1, not 0.)

-prefs
    Like the no-argument form of -demo, but brings up that program's Preferences panel by default.

-activate
    Tell xscreensaver to turn on immediately (that is, blank the screen, as if the user had been idle for long enough.) The screensaver will deactivate as soon as there is any user activity, as usual. It is useful to run this from a menu; you may wish to run it as
        sleep 5 ; xscreensaver-command -activate
    to be sure that you have time to take your hand off the mouse before the screensaver comes on. (Because if you jiggle the mouse, xscreensaver will notice, and deactivate.)

-deactivate
    This tells xscreensaver to pretend that there has just been user activity. This means that if the screensaver is active (the screen is blanked), then this command will cause the screen to un-blank as if there had been keyboard or mouse activity. If the screen is locked, then the password dialog will pop up first, as usual. If the screen is not blanked, then this simulated user activity will re-start the countdown (so, issuing the -deactivate command periodically is one way to prevent the screen from blanking.)

-cycle
    If the screensaver is active (the screen is blanked), then stop the current graphics demo and run a new one (chosen randomly.)

-next
    This is like either -activate or -cycle, depending on which is more appropriate, except that the graphics hack that will be run is the next one in the list, instead of a randomly-chosen one. In other words, repeatedly executing -next will cause the xscreensaver process to invoke each graphics demo sequentially. (Though using the -demo option is probably an easier way to accomplish that.)

-prev
    This is like -next, but cycles in the other direction.

-select number
    Like -activate, but runs the Nth element in the list of hacks. By knowing what is in the programs list, and in what order, you can use this to activate the screensaver with a particular graphics demo. (The first element in the list is numbered 1, not 0.)

-exit
    Causes the xscreensaver process to exit gracefully. This is roughly the same as killing the process with kill(1), but it is easier, since you don't need to first figure out the pid. Warning: never use kill -9 with xscreensaver while the screensaver is active. If you are using a virtual root window manager, that can leave things in an inconsistent state, and you may need to restart your window manager to repair the damage.

-lock
    Tells the running xscreensaver process to lock the screen immediately. This is like -activate, but forces locking as well, even if locking is not the default (that is, even if xscreensaver's lock resource is false, and even if the lockTimeout resource is non-zero.) Note that locking doesn't work unless the xscreensaver process is running as you. See xscreensaver(1) for details.

-throttle
    Temporarily switch to ``blank screen'' mode, and don't run any display modes at all, until the screensaver is next de-activated. This is useful if you're using a machine remotely, and you find that some display modes are using too much CPU. (If you want to do this permanently, that is, you want the screen saver to only blank the screen and not run demos at all, then set the programs resource to an empty list: See xscreensaver(1) for details.)

-unthrottle
    Turn `-throttle' mode off and resume normal behavior.

-version
    Prints the version of xscreensaver that is currently running on the display: that is, the actual version number of the running xscreensaver background process, rather than the version number of xscreensaver-command. (To see the version number of xscreensaver-command itself, use the -help option.)

-time
    Prints the time at which the screensaver last activated or deactivated (roughly, how long the user has been idle or non-idle: but not quite, since it only tells you when the screen became blanked or un-blanked.)

-restart
    Causes the screensaver process to exit and then restart with the same command line arguments as last time. Do this after you've changed the resource database, to cause xscreensaver to notice the changes. Warning: if you have a .xscreensaver file, this might not do what you expect. You're probably better off killing the existing xscreensaver (with xscreensaver-command -exit) and then launching it again. The important point is, you need to make sure that the xscreensaver process is running as you. If it's not, it won't be reading the right .xscreensaver file.

-watch
    Prints a line each time the screensaver changes state: when the screen blanks, locks, unblanks, or when the running hack is changed. This option never returns; it is intended for use by shell scripts that want to react to the screensaver in some way. An example of its output would be:
        BLANK Fri Nov  5 01:57:22 1999
        RUN 34
        RUN 79
        RUN 16
        LOCK Fri Nov  5 01:57:22 1999
        RUN 76
        RUN 12
        UNBLANK Fri Nov  5 02:05:59 1999
    The above shows the screensaver activating, running three different hacks, then locking (perhaps because the lock-timeout went off) then unblanking (because the user became active, and typed the correct password.) The hack numbers are their index in the `programs' list (starting with 1, not 0, as for the -select command.) For example, suppose you want to run a program that turns down the volume on your machine when the screen blanks, and turns it back up when the screen un-blanks. You could do that by running a Perl program like the following in the background. The following program tracks the output of the -watch command and reacts accordingly:
        #!/usr/bin/perl
        my $blanked = 0;
        open (IN, "xscreensaver-command -watch |");
        while (<IN>) {
            if (m/^(BLANK|LOCK)/) {
                if (!$blanked) {
                    system "sound-off";
                    $blanked = 1;
                }
            } elsif (m/^UNBLANK/) {
                system "sound-on";
                $blanked = 0;
            }
        }
    Note that LOCK might come either with or without a preceeding BLANK (depending on whether the lock-timeout is non-zero), so the above program keeps track of both of them.

DIAGNOSTICS
If an error occurs while communicating with the xscreensaver daemon, or if the daemon reports an error, a diagnostic message will be printed to stderr, and xscreensaver-command will exit with a non-zero value. If the command is accepted, an indication of this will be printed to stdout, and the exit value will be zero.

ENVIRONMENT

DISPLAY
    to get the host and display number of the screen whose saver is to be manipulated.

PATH
    to find the executable to restart (for the -restart command). Note that this variable is consulted in the environment of the xscreensaver process, not the xscreensaver-command process.

UPGRADES
The latest version of xscreensaver(1) and related tools can always be found at http://www.jwz.org/xscreensaver/

SEE ALSO
X(1), xscreensaver(1) xscreensaver-demo(1)

COPYRIGHT
Copyright © 1992, 1993, 1997, 1998, 1999, 2000, 2001, 2002 by Jamie Zawinski. Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. No representations are made about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.

AUTHOR
Jamie Zawinski <jwz@jwz.org>, 13-aug-92. Please let me know if you find any bugs or make any improvements.